angular自带的一些api,如何使用Angular在一个函数上调用多个API？

I need to call 4 different API's on a single function which is need to execute one after another as my previous API result will use the next Call as a param. For example: I have a call API for geo Ip, then I need to call an another API which I need to pass lat and long which I have got from first API call.

How can I achieve this task on angular 4?

I heard about some methods like flatmap and forkjoin. Is this method can use? (I didn't have any code as I am little bit confused).

解决方案

If you can use es6 you can use async and await

async makeCalls() {

try {

let response1 = await this.http.get(firstEndpointUrl).toPromise();

let secondEndpointUrl = 'someUrl/' + response1.json().id;

let response2 = await this.http.get(secondEndpointUrl).toPromise();

let thirdEndpointUrl = 'someUrl/' + response2.json().id;

let response3 = await this.http.get(thirdEndpointUrl).toPromise();

return response3.json();

} catch (error) {

// handle error

}

}